JP2007245090A - Method and device for drying coated film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and a device for drying a coated film capable of suppressing the generation of a splotch on a coated film and performing even drying. <P>SOLUTION: The method for drying a coated film formed by applying a coating solution 12a containing an organic solvent onto a travelling longitudinal support 12, wherein a coated film surface of the support 12 to be dried is enclosed by providing a drying zone 14 just after coating, and a drying wind 46 having an entrapped wind direction component of almost the same direction as in an entrapped wind 44 accompanied with a conveyance of the support 12 is blown out from one end to the other end of the longitudinal support width direction in the zone 14. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a coating film drying method and apparatus, and in particular, in the production of an optical compensation sheet or the like, a long and wide coating film surface formed by applying a coating liquid containing an organic solvent to a long support. The present invention relates to a drying method and apparatus for drying.

  In order to improve viewing angle characteristics in a liquid crystal display device, an optical compensation sheet is provided as a retardation plate between a pair of polarizing plates and a liquid crystal cell. A long optical compensation sheet is formed by applying a coating liquid containing an alignment film forming resin on the surface of a long transparent film, and then performing a rubbing treatment to form an alignment film, and a liquid crystal is formed on the alignment film. It can manufacture by apply | coating the coating liquid containing an adhesive discotic compound, and drying the apply | coated coating film. The method for drying a coating liquid containing a liquid crystalline discotic compound disclosed in Patent Document 1 is applied until the coating liquid containing the liquid crystalline discotic compound is applied on the alignment film and then dried with a regular drying apparatus. Initial drying is performed under air-conditioning conditions to mainly evaporate the organic solvent in the coating solution. In the optical compensation sheet produced by this method, the broad spots A (shown by thin lines) and the sharp spots B (shown by thick lines) as shown in FIG. The two types of spots (unevenness) A and B occurred, and there was a problem that the yield of the product was lowered in some cases.

Therefore, in Patent Document 2, a drying zone is provided immediately after coating, and a one-way flow of drying air flowing from one direction side to the other direction side in the widthwise width of the elongated support is generated in the drying process. It is disclosed to suppress broad spots A and sharp spots B.
JP-A-9-73081 JP 2001-170547 A

  However, in Patent Document 2, although broad spots A and sharp spots B of the coating film of Patent Document 1 can be suppressed, as shown in FIG. As a new spot-like defect, a straight sharp spot C and a diagonally sharp spot near the end on the side where the drying wind in the width direction of the long support is blown off are generated as a new spot-like defect. There was a problem that spots D would occur.

  The present invention has been made in view of such circumstances, a drying method capable of effectively suppressing the occurrence of all spot-like defects on the coating film surface during drying, and drying the coating film surface uniformly, and An object is to provide an apparatus.

  In order to achieve the above object, the invention according to claim 1 is a method for drying a coating film formed by applying a coating solution containing an organic solvent to a traveling long support, and a drying zone is provided immediately after the coating. The long support body surrounds the coating film surface to be dried of the long support body that travels, and extends from the one end side to the other end side in the width direction of the long support body in the drying zone. A drying method of a coating film is provided, characterized in that drying air having a companion air direction component in a direction substantially the same as the accompanying air accompanying the conveyance of the coating film is blown out.

  The inventor of the present invention has found that the straight-shaped sharp spots and the slanted-shaped sharp spots due to the unidirectional flow of dry air flowing from one end side to the other end side in the width direction of the long support are As a result of intensive studies on the cause of the dry air outlet near the end, the following was found. That is, accompanying the conveyance of the long support, an entrainment wind in the same direction as the conveyance direction of the long support is generated on the coating film surface. And on the coating film surface near the dry air outlet side where the wind speed of the dry air is not attenuated, the accompanying air and the dry air flowing in the direction perpendicular to the accompanying air collide to generate air turbulence (vortex), It has been found that due to this turbulence of air current, straight sharp spots and oblique sharp spots are generated. Therefore, the present inventors have found that straight sharp spots and oblique sharp spots can be suppressed by reducing airflow turbulence caused by the collision between the accompanying wind and the dry wind.

  Then, when this inventor tried the experiment of the countermeasure which relieve | moderates turbulence of airflow, dry wind is accompanied at least 100 mm (preferably to 200 mm) from the said one end side edge part of a elongate support body width direction. It was found that air turbulence can be alleviated by having a wind direction component. That is, by providing a companion air direction component to the dry air, air flow disturbance on the dry air outlet side of the long support is alleviated, and the drying conditions (the situation where the dry air hits the coating film surface of the long support) Since it can be made uniform in the entire width direction of the long support, straight sharp spots and oblique sharp spots can be suppressed. In other words, by straightening the thickness of the entrained air flowing on the coating film surface over the entire length of the long support, it is possible to suppress straight sharp spots and oblique sharp spots. .

  In addition, in the coating film surface position which entered the central part side further from the coating film surface position near the blower outlet side from which the drying air is blown out, the wind speed of the drying air is attenuated, and the wind speed of the accompanying air becomes dominant. There will be no air turbulence.

  Therefore, according to claim 1, a drying zone is provided immediately after coating, and the long support is transported from the one end side to the other end side in the long support width direction in the drying zone. Since the drying air having the companion air direction component in the same direction as the accompanying air is blown out, not only the conventional broad spots A and sharp spots B but also the drying wind blowing in the width direction of the long support at the time of drying. It is also possible to suppress straight sharp spots C and oblique sharp spots D generated near the exit end. Thereby, while being able to suppress a patch-like application | coating defect, a coating film can be dried uniformly.

  According to a second aspect of the present invention, in the first aspect of the invention, the dry wind has a companion wind direction component at least from the one end side end portion in the width direction of the elongated support to 100 mm. And

  This is because, as described above, the turbulence of the airflow occurs up to 100 mm from the one end side end in the long support width direction.

  According to a third aspect of the present invention, in the first or second aspect of the present invention, the accompanying wind direction component is generated by applying a swirling flow to the dry wind.

  Claim 3 shows a preferable example for imparting the accompanying wind direction component to the dry wind. If the drying air to which the swirl flow is applied is blown from one end in the width direction of the long support toward the other end, the surface of the coating film near the end on the side of the drying air outlet in the width direction of the long support Can form a wind direction component in the same direction as the entrained flow.

  The invention according to claim 4 is the invention according to any one of claims 1 to 3, wherein the wind speed of the companion wind direction component at the coating film surface position in the vicinity of the air outlet side is the same as the wind speed of the accompanying wind. It is characterized by being.

  This is because if the wind speed of the accompanying wind direction component is the same as the wind speed of the accompanying wind, the above-described air turbulence can be further suppressed.

  The invention according to claim 5 is the invention according to any one of claims 1 to 4, wherein the dry air is blown out through a flow regulating member.

  This is because the wind speed of the drying air can be made uniform by blowing the drying air through the rectifying member.

  The invention according to claim 6 is the invention according to claim 5, wherein the flow regulating member has a honeycomb structure.

  According to the sixth aspect, since the rectifying member is a honeycomb structure member, it is possible to make the drying air flow in one direction and make the wind velocity distribution uniform.

  The invention according to claim 7 is the invention according to any one of claims 1 to 6, wherein the dry air contains the same solvent gas as the organic solvent.

  According to claim 7, by containing the same solvent gas as the organic solvent of the coating liquid in the drying air, the concentration of the organic solvent in the drying zone can always be kept constant. Nonuniformity can be eliminated. Therefore, the coating film can be further dried uniformly.

  The invention according to claim 8 is the invention according to any one of claims 1 to 7, wherein the drying zone is divided into a plurality of divided zones in the traveling direction of the elongated support, and each divided zone is divided. And adjusting the wind speed of the dry air.

  According to the eighth aspect, since the drying zone is divided into a plurality of divided zones, and the speed of the drying air is adjusted for each of the divided zones, the drying conditions of the coating film can be finely set. Can be dried uniformly.

  The invention according to claim 9 is characterized in that, in the invention according to claim 8, the air volume of the dry air and the air volume of the entrained air direction component are adjusted for each of the divided zones.

  Since the air volume of the drying air and the air volume of the accompanying air direction component are adjusted for each divided zone, the drying conditions of the coating film can be set more finely, and the coating film can be dried uniformly. it can.

  In order to achieve the above object, the invention according to claim 10 is a coating film drying apparatus formed by applying a coating solution containing an organic solvent to a traveling long support by a coating machine. A drying apparatus main body that is provided immediately after and forms a drying zone that surrounds the coating film surface to be dried of the traveling long support, and one end side of the long support in the width direction within the drying zone From the side toward the other end side, there is provided dry air supply means for applying dry air having a companion air direction component in substantially the same direction as the accompanying air accompanying the conveyance of the elongated support. To do.

  Claim 10 constitutes the present invention as an apparatus invention. According to the present invention, not only the conventional broad spots A and sharp spots B during drying but also drying in the width direction of the long support. It is also possible to suppress straight sharp spots C and oblique sharp spots D that occur in the vicinity of the wind outlet side end. Thereby, while being able to suppress a patch-like application | coating defect, a coating film can be dried uniformly.

  An eleventh aspect of the present invention is the method according to the tenth aspect, wherein the dry air supply means includes a box body in which a dry air outlet is formed on a side surface, and a dry air supply that supplies the dry air to the box body. And a swirling air supply pipe for supplying air for generating a swirling flow in the dry air supplied into the box.

  According to the eleventh aspect, since the swirl flow air supply pipe for supplying the air for generating the swirl flow is provided to the dry wind supplied from the dry wind supply pipe into the box body, it is formed on the side surface of the box. From the blower outlet, dry air having a swirl component can be blown from one end side in the widthwise direction of the elongated support toward one direction on the other end side. As a result, up to the coating film surface position near the air outlet side from which the drying air is blown out (until the position where the wind speed of the swirl flow component is not attenuated), the drying air is substantially in the same direction as the accompanying air accompanying the conveyance of the long support. Therefore, the turbulence of the airflow caused by the collision between the accompanying air and the drying air in the direction orthogonal to the accompanying air can be reduced.

  A twelfth aspect of the invention according to claim 11, wherein the ratio of the amount of dry air supplied from the dry air supply pipe into the box and the amount of swirl air supplied from the swirl air supply pipe into the box is The range is from 1: 0.1 to 1: 2.

  According to the twelfth aspect, when the ratio of the dry air volume and the swirling air volume is in the range of 1: 0.1 to 1: 2, air current turbulence can be effectively suppressed. If the amount of swirling air is less than 0.1 when the amount of dry air is 1, the effect of alleviating air turbulence is small, and if it exceeds 2 the air turbulence is newly developed.

According to a thirteenth aspect of the present invention, in the tenth or eleventh aspect, after the dry air supplied from the dry air supply pipe into the box body is rectified by a rectifying member, air is supplied from the swirl air supply pipe. A swirl flow is formed by being supplied.
This is because a swirl flow having no wind speed distribution can be formed by forming a swirl flow in the dry air after the dry air has been rectified.

  The invention described in claim 14 is characterized in that, in claim 13, the rectifying means is constituted by a member having a honeycomb structure.

  According to the fourteenth aspect, since the rectifying means is constituted by a honeycomb structure member, the drying air can be made to flow in one direction and the wind speed distribution can be made uniform.

  A fifteenth aspect of the present invention is characterized in that, in any one of the tenth to fourteenth aspects, the swirling air supply pipe is provided with a fluid ejection nozzle at a tip portion.

  According to the fifteenth aspect, since the swirling air supply pipe is provided with the fluid ejection nozzle at the tip, it can effectively form a swirling flow with respect to the dry air supplied to the box.

  The invention according to claim 16 is the method according to any one of claims 10 to 15, wherein the drying zone is partitioned by a partition plate perpendicular to the traveling direction of the elongated support to form a plurality of divided zones. The dry air supply means is provided for each divided zone.

  According to claim 16, the drying zone is partitioned by a partition plate to form a plurality of divided zones, and the drying air supply means is provided for each of the divided zones, so the drying conditions of the coating film can be set finely, The coating film can be dried uniformly.

  According to the present invention, the dry wind blown from one end to the other end in the width direction of the long support is the accompanying wind direction component in the same direction on the coating film surface as the accompanying air accompanying the conveyance of the long support. Therefore, the spots generated on the drying air outlet side of the long support during drying can be suppressed, and uniform drying can be performed.

  Hereinafter, preferred embodiments of a coating film drying method and apparatus according to the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a side view showing the overall configuration of the coating film drying apparatus of the present invention, and FIG. 2 is a plan view of FIG. 1 viewed from above. In FIG. 2, the upper lid 34 shown in FIG. 1 is removed and shown.

  As shown in FIG. 1 or FIG. 2, the coating film drying apparatus 10 of the present invention mainly passes a traveling long support 12 (hereinafter referred to as “web 12”) to dry the coating film. The drying apparatus main body 16 that forms the drying zone 14 to be performed, and the drying air supply means 18A, 18B, 18C, 18D, 18E for blowing the drying air from the one end side to the other end side in the width direction of the web 12 into the drying zone 14 , 18F, 18G, and dry air exhaust means 18H, 18I, 18J, 18K, 18L, 18M, 18N for discharging the dry air. The drying apparatus 10 is provided immediately after a coating machine 20 that applies a coating solution containing an organic solvent to a traveling web 12.

  As an example of the present embodiment, the web 12 has a layer to be an alignment film by rubbing a previously applied alignment film forming resin, and the coating liquid contains a liquid crystalline discotic compound. An example of an organic solvent-based coating solution will be described.

  As the coating machine 20, for example, a bar coating device including a wire bar 20 </ b> A can be used, and a coating liquid is applied to the lower surface of the web 12 that is supported by a plurality of pass rollers 22, 24, 26 and applied. A film is formed.

  The drying device main body 16 is provided immediately after the coating machine 20, and is formed in a long rectangular box shape along the coating film surface side (the lower surface side of the web) of the traveling web 12, and among the sides of the box body The side of the coated film surface side (the upper side of the box) is cut off. Thereby, the drying zone 14 surrounding the coating film surface to be dried of the traveling web 12 is formed. The drying zone 14 divides the drying apparatus main body 16 with a plurality of partition plates 28, 28... Orthogonal to the traveling direction of the web 12, thereby dividing the plurality of divided zones 14 A, 14 B, 14 C, 14 D, 14 E, 14 F, 14 G ( In this test, it is divided into 7 divided zones. In this case, the distance between the upper end of the partition plate 28 that divides the drying zone 14 and the coating film surface formed on the web 12 is preferably in the range of 0.5 mm to 12 mm, more preferably in the range of 1 mm to 10 mm. . Further, the width of the drying apparatus main body 16 is formed to be larger than the width of the web 12, and an upper lid 34 (see FIG. 1) is provided above the drying zone 14.

  Immediately after the coating liquid is applied to the web 12 supported by the pass rollers 22, 24, and 26 by the wire bar 20 </ b> A of the coating machine 20, the coating film surface is initially dried by the drying device 10. In this initial drying, it is preferable to start drying with a drying air immediately after application, and immediately after application within 5 seconds at the latest.

  Dry air supply means 18A, 18B, 18C, 18D, 18E, 18F, and 18G are provided on one end side in the width direction for each of the divided drying zones 14A, 14B, 14C, 14D, 14E, 14F, and 14G. In addition, dry air exhaust means 18H, 18I, 18J, 18K, 18L, 18M, and 18N are provided on the other end side.

  3 is a cross-sectional view in the web width direction in the divided zone 14C of the drying zone 14, and FIG. 4 is a cross-sectional view in the web conveyance direction in the divided zone 14C. FIG. 5 is a conceptual diagram showing dry air supply means and dry air exhaust means. The structure of the divided zones other than the divided zone 14C is the same.

  As shown in FIG. 3, the divided zone 14 </ b> C is provided with a drying air supply means 18 that blows the drying air 42 from one end side to the other end side in the web 12 width direction.

  As shown in FIGS. 3 and 5, the drying air supply means 18 includes a box body 21 having a drying air outlet a formed on the side surface, and a drying air supply pipe 17 </ b> C that supplies the drying air into the box body 21. And a swirling air supply pipe 40 </ b> C that supplies air for generating a swirling flow in the dry air supplied into the box body 21, and the rectifying plate 19. The rectifying plate 19 divides the box 21 into a front chamber 21A having a blower outlet a and a rear chamber 21B having no blower outlet a, and a drying air supply pipe 17C is connected to the center of the lower surface of the rear chamber 21B. A swirl air supply pipe 40C is connected to one end of the upper surface of 21A. According to the drying air supply means 18 having such a structure, the drying air is supplied from the drying air supply pipe 17C into the box body 21, while the air is supplied into the box body 21 from the swirling air supply pipe 40C. Is blown out from the air outlet a formed on the side surface of the box body 21. This dry air supply means can control the air volume (wind speed) of the dry air individually for each of the divided zones 14A to 14G. The dry air blown out from the dry air supply means 18A to 18G is preferably air conditioned air whose temperature and humidity are air conditioned.

As shown in FIG. 3, the dry air exhaust means 18J is disposed so as to face the dry air supply means 18C, and has a box body 23 having a dry air discharge port b formed on a side surface, and an exhaust gas connected to the box body 23. It is comprised with the pipe | tube 17J.
Thus, the swirl flow 46 is provided from the dry air supply means 18C toward the dry air exhaust means 18J, that is, from one end side (blow-out port side) to the other end side (discharge port side) in the web width direction. Dry air can be blown out in one direction 42.

  The drying air is supplied from the drying air supply pipe 17C to the box 21 and the air is supplied from the swirling air supply pipe 40C to the box 21, but the drying air supply pipe 17C is branched to supply the swirling air. By connecting to the tube 40C, dry air may be blown out from the swirling air supply tube 40C. Further, in the present embodiment, the swirl flow is generated by the dry air supply pipe 17C and the swirl air supply pipe 40C. For example, instead of the swirl air supply pipe 40C, a fan is installed in the box 21. It may be provided, or a rectifying member with a turning fin may be provided. In short, the drying air having the swirling flow 46 may be blown out from one end side (blowout port side) in the web width direction to the other end side (discharge port side).

  Incidentally, as can be seen from FIG. 4, accompanying the web 12 is transported, an accompanying wind is generated on the coating film surface in the same direction as the transport direction of the web 12, and the accompanying wind collides with the partition plate 28 and the partition plate 28. Is turned into a swirling flow in the divided zone 14C.

  Then, as in the past, the coating film surface in the vicinity of the drying air outlet (near the outlet a) where the air velocity of the drying air is not attenuated only by the air flow of the drying air from one end to the other end in the web width direction. Above, the accompanying air and the drying air orthogonal to the accompanying air collide, and airflow turbulence occurs on the coating film surface on the web 12 outlet side. Due to this turbulence, straight sharp spots C and oblique sharp spots D are generated in the vicinity of the outlet side in the web width direction. The spots C and D are generated at a position of about 100 mm from the end on the outlet side in the web width direction.

  Therefore, in the present invention, in order to suppress the occurrence of unevenness on the air outlet side in the web width direction due to the influence of the airflow turbulence, as shown in FIG. 3, the dry air exhaust from the air outlet a of the dry air supply means 18 is performed. By entraining the drying air having the swirl flow 46 toward the outlet b of the means 18J, the entrainment air flowing in the same direction as the accompanying air 44 (see FIG. 4) accompanying the conveyance of the web 12 on the coating film surface 12a of the web 12. The wind direction component 46A was added.

  In this way, the turbulence of the air flow on the drying air outlet side of the web 12 is alleviated by the drying air having the swirl flow 46, and the drying conditions (the situation in which the drying air hits the coating film surface of the long support) are controlled. It can be the same as the part other than the exit side. As a result, not only the conventional broad spots A and sharp spots B during drying, but also the straight sharp spots C and the diagonally sharp spots D generated in the vicinity of the dry air outlet side end in the web width direction. Can also be suppressed.

  Furthermore, since the rectifying member 19 is attached to the dry air supply means 18, the dry air 42 can be rectified by the rectifying member 19, so that the wind speed distribution can be made uniform. The rectifying member 19 is preferably a honeycomb structure member. The honeycomb structure member has cell shapes such as hexagonal, OX, flex, bisecto, and feather, but may be any shape. FIG. 6 shows a hexagonal cell shape as an example of the honeycomb structure member 19. However, since each cell 19 a is fine and thick, the rectifying effect is large.

  In this case, the dry air supplied into the box 21 from the dry air supply pipe 17C is rectified by the rectifying member 19, and then air is supplied from the swirl air supply pipe 40C to form a swirl flow. preferable. This is because a swirl flow having no wind speed distribution can be formed by forming a swirl flow in the dry air after the dry air has been rectified.

  The ratio of the amount of dry air supplied from the dry air supply pipe 17C into the box body 21 and the amount of swirling air supplied from the swirling air supply pipe 40C into the box body 21 is 1: 0.1 to 1: 2. A range is preferable. Airflow turbulence can be effectively suppressed because the ratio of the dry air volume and the swirling air volume is in the range of 1: 0.1 to 1: 2. Here, if the amount of swirling air is less than 0.1 when the amount of dry air is 1, the effect of relieving air turbulence is low, and if the amount of swirling air is greater than 2 when the amount of air is 1, New air current turbulence appears and is not effective in eliminating the spots.

  In addition, by providing the drying zone 14, a dry environment is formed in which the organic solvent evaporated from the coating film surface covers the coating film surface. Under this dry environment, the dry air blown from the dry air supply means 18A to 18G to the divided zones 14A to 14G is exhausted from the dry air exhaust means 18H to 18N, so that each of the divided zones 14A to 14G is swirled. The drying air having a flow flows in one direction from one end side (blow-out port side) to the other end side (discharge port side) in the web width direction. As a result, the drying air containing the evaporated organic solvent is exhausted from the drying air exhaust means 18H to 18N and gradually dried while the coating film surface is covered with the organic solvent. In this case, if the air volume (air speed) of the dry air blown from the air outlets 18A to 18G of the dry air supply means 18A to 18G is too large, the organic solvent is not evenly covered on the coating film surface. It is necessary to prevent the air volume from becoming too large. Thereby, since the organic solvent concentration in the vicinity of the coating film surface can be made uniform, the organic solvent can be uniformly evaporated from each part of the coating film surface.

  In this case, when the web 12 travels in the drying zone 14, the organic solvent concentration in the vicinity of the coating film on the inlet side and the outlet side in the web conveying direction of the drying zone 14 may be different. This can be solved by dividing the zone into the divided zones 14A to 14G. That is, by controlling the air volume of each of the dry air supply means 18A to 18G provided in each of the seven divided zones 14A to 14G and adjusting the wind speed of the dry air flowing through each of the divided zones 14A to 14G, drying is performed. The difference in the concentration of the organic solvent in the vicinity of the coating film surface on the inlet side and the outlet side of the zone 14 can be eliminated.

  As the drying air, for example, air-conditioning air such as an air-conditioning room in which the drying device 10 is installed can be used. However, the air containing the same solvent as the organic solvent contained in the coating liquid is used as the drying air supply means 18A. You may make it blow out from ~ 18G.

  The web 12 used in the present invention is generally polyethylene terephthalate, polyethylene-2,6 naphthalate having a width of 0.3 to 5 m, a length of 45 to 10,000 m, and a thickness of 5 to 200 μm, cellulose diacetate, cellulose triacetate, and cellulose acetate. Coating or laminating α-polyolefins with 2 to 10 carbon atoms such as plastic film such as propionate, polyvinyl chloride, polyvinylidene chloride, polycarbonate, polyimide, polyamide, paper, polyethylene, polypropylene, ethylene butene copolymer Paper, metal foil such as aluminum, copper, tin, or the like, or those obtained by forming a preliminary processing layer on the surface of a belt-like substrate. Further, the above-described web 12 is coated with an optical compensation sheet coating solution, a magnetic coating solution, a photographic photosensitive coating solution, a surface protecting, antistatic or slippery coating solution on the surface, dried, and then desired. Those that are cut into lengths and widths are included, and representative examples thereof include optical compensation sheets, various photographic films, photographic paper, magnetic tape, PS plates, and the like.

  In addition to the bar coating method described above, curtain coating method, extrusion coating method, roll coating method, dip coating method, spin coating method, print coating method, spray coating method and slide coating method are used as the coating method for the coating liquid. be able to. In particular, a bar coating method, an extrusion coating method, and a slide coating method can be suitably used.

  In the present invention, the number of coating layers of the coating solution applied simultaneously is not limited to a single layer, and can be applied to a simultaneous multilayer coating method as necessary.

  FIG. 7 shows a case where the drying device 10 of the present invention is incorporated in the optical compensation sheet manufacturing process, and the effect of adjusting the amount of dry air blown from each of the dry air supply means 18A to 18G of the drying device 10. Was investigated in relation to the state of occurrence of unevenness (unevenness) in the manufactured optical compensation sheet.

About the air volume of each dry air supply means 18A-18G of the drying apparatus 10, it performs about 3 tests of 1-3 of Table 1, and shows the wind speed of the dry wind which flows through each divided zone 14A-14G in each test in Table 1. It was. Further, the three tests 1 to 3 were performed under the following conditions a to c, respectively.
a) Swirling air volume is 0 (zero)
b) Dry air volume: Swirl air volume = 1: 0.2
c) Dry air volume: swirling air volume = 1: 1
First, the optical compensation sheet manufacturing process will be described. As shown in FIG. 7, the web 12 delivered by the delivery device 40 is supported by a plurality of guide rollers 42, 42. The paper is taken up by a winder 52 after passing through the drying apparatus 10 of the present invention for drying, the drying zone 46 for performing the main drying, the heating zone 48 and the ultraviolet lamp 50.

  As the web 12, triacetyl cellulose (Fujitack, manufactured by Fuji Photo Film Co., Ltd.) having a thickness of 100 μm was used. An alignment film formed by applying 25 ml of a 2 weight percent solution of long-chain alkyl-modified poval (MP-203, manufactured by Kuraray Co., Ltd.) to the surface of the web 12 and then drying at 60 ° C. for 1 minute. The web 12 on which the resin layer was formed was rubbed on the surface of the resin layer while being transported and run at 18 m / min to form an alignment film. The pressing pressure of the rubbing roller 54 in the rubbing process was 98 Pa (10 kgf / cm 2) per cm 2 of the alignment film resin layer, and the rotational peripheral speed was 5.0 m / sec.

Then, on the alignment film obtained by rubbing the resin layer for alignment film, the coating liquid 12a has a weight ratio of (3) of the discotic compound TE-8 and (5) of TE-8 at 4: A coating liquid containing a liquid crystalline compound that is a 40 wt% methyl ethyl ketone solution of a mixture obtained by adding 1 wt% of a photopolymerization initiator (Irgacure 907, manufactured by Ciba Geigy Japan Co., Ltd.) to the above mixture was used as the mixture of No. 1 . While running the web 12 at a running speed of 18 m / min, this coating solution was applied onto the alignment film with a wire bar 20A so that the amount of the coating solution was 5 ml per m ^{2 of} web. And immediately after application | coating, initial drying was performed using the drying apparatus 10 of this invention.

  The interval between the upper end of the partition plate 28 that divides the drying zone 14 into seven and the coating film surface was set in the range of 5 to 9 mm. Further, the web 12 initially dried by the drying apparatus 10 of the present invention passes through a drying zone 46 adjusted to 100 ° C. and a heating zone 48 adjusted to 130 ° C. to form a nematic phase, and then this orientation While continuously transporting the web 12 coated with the film and the liquid crystal compound, the surface of the liquid crystal layer was irradiated with ultraviolet rays by an ultraviolet lamp 50.

  In addition, in the occurrence of spots in Table 1, Δ indicates that spots occurred but the frequency of occurrence is small, ○ indicates that spots were hardly generated, and ◎ indicates that spots were not completely generated. Indicates.

その結果、表１から分かるように、各分割ゾーンの風速を全て同じ０．５ｍ／秒とした試験１−ａ〜１−ｃでは、ブロード斑Ａが発生し、シャープ斑Ｂは発生しなかった。

As a result, as can be seen from Table 1, broad spots A occurred and sharp spots B did not occur in Tests 1-a to 1-c in which the wind speeds of the respective divided zones were all set to the same 0.5 m / second. .

  On the other hand, in Test 1-a in which the amount of swirling air was 0, straight sharp spots C and oblique sharp spots D were generated on the dry air outlet side. However, in Tests 1-b and 1-c conducted with dry air having a swirl flow, the expression of straight sharp spots C and oblique sharp spots D could be reduced.

  Further, the wind speed of the divided zone 14A close to the coating machine 20 is 1.0 m / second, the wind speed of the next divided zone 14B is 1.5 m / second, and the wind speed of the subsequent divided zones 14C to 14G is 0.5 m / second. In Tests 2-a to 2-c, neither broad spots A nor sharp spots B were generated, and the results were good.

  On the other hand, in Test 2-a in which the amount of swirling air was 0, straight sharp spots C and oblique sharp spots D were generated on the dry air outlet side. However, in Tests 2-b and 2-c performed with dry air having a swirl flow, the expression of straight sharp spots C and oblique sharp spots D could be reduced.

  Further, the wind speed of the divided zone 14A is 1.0 m / second, the wind speed of the next divided zone 14B is 1.5 m / second, the wind speed of the divided zones 14C and 14D is 0.5 m / second, and the divided zones 14E, 14F, Tests 3-a to 3-c in which the wind speed of 14G was 2.0 m / second occurred both with broad spots A and sharp spots B, and were the worst evaluations among Tests 1 to 3.

  On the other hand, in Test 3-a in which the amount of swirling air was 0 (zero), straight sharp spots C and oblique sharp spots D were generated on the dry air outlet side. However, in Test 3-c carried out with dry air having a swirl flow, the expression of linear sharp spots C could be reduced.

  Thus, installing the drying apparatus 10 immediately after coating and dividing the drying zone and setting the optimum wind speed by the individual exhaust means is effective for suppressing the spots A and B generated in the initial drying process. It turns out that. Furthermore, it turned out that it is possible to reduce the straight sharp spots C and the slanted sharp spots D generated on the drying air outlet side by drying with the drying air having a swirl flow. In any of Tests 1 to 3, it can be seen that, by increasing the amount of swirling air, the spots C first decrease and then the spots D decrease.

  By the way, in Tests 1 to 3, the evaluation level of the spots was different, but this was because the wind speed of each drying zone was changed to form conditions that make it easy for spots to appear, and conditions that make it difficult for them to appear. Spots are less likely to appear in the order of 1 and Test 2.

Furthermore, in order to confirm the effect of the rectifying member, the following d and e conditions were performed in tests 1 to 3, respectively.
c) Dry air volume: swirling air volume = 1: 1
d) Dry air volume: swirling air volume = 1: 1, rectifying member; wire mesh e) Dry air volume: swirling air volume = 1: 1, rectifying member: perforated plate Note that pressure loss: ΔP (Pa), average wind speed: v (m / sec), ξ (kg / m ³ ) defined by ΔP≡ξ × v ² is referred to as a pressure loss coefficient. However, the wire mesh and perforated plate of the rectifying member used the following (where v is Passing wind speed (different from wire gap for wire mesh, wind speed when passing through holes for perforated plate).
Wire mesh: Nominal # 350 (plain weave), wire diameter 30 μm, wire spacing 42 μm, ξ = about 3 (kg / m ³ )
Perforated plate: Hole diameter 5mm, hole interval 8mm, plover arrangement, ξ = approx. 30 (kg / m ³ )

表２の結果から分かるように、整流部材を設けることで斑の発現を更に抑制することができる。特に、整流部材がハニカム構造である多孔板のほうが良い結果が得られていることが分かる。

As can be seen from the results in Table 2, it is possible to further suppress the appearance of plaques by providing a rectifying member. In particular, it can be seen that better results have been obtained with a perforated plate in which the rectifying member has a honeycomb structure.

Side view of the drying apparatus of the present invention Plan view of the drying apparatus of the present invention Sectional drawing which looked at the division | segmentation zone of the drying apparatus of this invention in the width direction of the web Sectional drawing which looked at the division | segmentation zone of the drying apparatus of this invention in the conveyance direction of the web Schematic showing vents Schematic plan view showing an example of a honeycomb structure member Process diagram incorporating the drying device of the present invention into the optical compensation sheet manufacturing process Spots (unevenness) generated by the conventional drying method Spots of unevenness generated by a drying method using unidirectional drying air

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Drying device, 12 ... Web, 14 ... Drying zone, 14A-14G ... Dividing zone, 16 ... Drying device main body, 18A-18G ... Dry air supply means, 18H-18N ... Dry air exhaust means, 19 ... Rectification member (Honeycomb structure member), 19a ... cell, 20 ... coating machine, 22, 24, 26 ... backup roller, 28 ... partition plate, 42 ... drying wind, 44 ... accompanying wind, 46 ... swirling wind, A ... broad spots , B ... sharp spots, C ... straight sharp spots, D ... diagonally sharp spots

Claims (16)

In the drying method of the coating film formed by applying a coating solution containing an organic solvent to the long support that travels,
Immediately after the application, a drying zone is provided to surround the coating film surface to be dried of the elongate support traveling,
Dry air having a companion air direction component in the same direction as the accompanying air accompanying conveyance of the long support from the one end side in the width direction of the long support to the other end side in the drying zone. A method for drying a coating film, wherein   2. The method of drying a coating film according to claim 1, wherein the drying air has a companion air direction component at least from the one end side end in the width direction of the elongated support to 100 mm.   3. The coating film drying method according to claim 1, wherein the accompanying wind direction component is generated by applying a swirling flow to the drying wind.   The method for drying a coating film according to any one of claims 1 to 3, wherein the wind speed of the accompanying wind direction component is the same as the wind speed of the accompanying wind.   The method of drying a coating film according to claim 1, wherein the drying air is blown out through a rectifying member.   6. The coating film drying method according to claim 5, wherein the flow regulating member has a honeycomb structure.   The said drying wind contains the same solvent gas as the said organic solvent, The drying method of the coating film of any one of Claims 1-6 characterized by the above-mentioned.   8. The method according to claim 1, wherein the drying zone is divided into a plurality of divided zones in the traveling direction of the elongated support, and the wind speed of the drying air is adjusted for each divided zone. The drying method of the coating film as described.   9. The method for drying a coating film according to claim 8, wherein the air volume of the dry air and the air volume of the accompanying air direction component are adjusted for each of the divided zones. In a coating film drying apparatus formed by applying a coating solution containing an organic solvent to a long supporting body traveling by a coating machine,
A drying apparatus main body that is provided immediately after the coating machine and forms a drying zone that surrounds the coating film surface to be dried of the elongated support that runs;
Dry air having an accompanying air direction component in substantially the same direction as the accompanying air accompanying the conveyance of the elongated support from one end side to the other end side in the width direction of the elongated support in the drying zone. An apparatus for drying a coating film, characterized in that a drying air supply means for imparting water is provided. The dry air supply means includes
A box body in which the outlet of the dry air is formed on a side surface;
A drying air supply pipe for supplying drying air into the box;
11. The coating film drying apparatus according to claim 10, further comprising a swirling air supply pipe for supplying air for generating a swirling flow in the drying air supplied into the box.   The ratio of the amount of dry air supplied from the dry air supply pipe into the box and the amount of swirl air supplied from the swirl air supply pipe into the box is in the range of 1: 0.1 to 1: 2. The apparatus for drying a coating film according to claim 11.   The dry air supplied into the box from the dry air supply pipe is rectified by a rectifying member, and then air is supplied from the swirl air supply pipe to form a swirl flow. 10 or 11 coating film drying apparatus.   14. The coating film drying apparatus according to claim 13, wherein the rectifying means is constituted by a member having a honeycomb structure.   The coating film drying apparatus according to claim 10, wherein the swirl air supply pipe includes a fluid ejection nozzle at a tip portion.   The drying zone is partitioned by a partition plate orthogonal to the traveling direction of the elongated support to form a plurality of divided zones, and the drying air supply means is provided for each divided zone. The coating film drying apparatus according to any one of 9 to 15.

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